Ignition system



Feb. 12, 1946.

J. R. HARKNESS IGNITION SYSTEM Filed Oct. 31,

, I I I I I v I 1 v I I I I I I I I I! mm?! 0 n n v 4 Inventor Joseph R.Har'hness,

Hus Attornsg.

Pa tented Feb. 12,

2,394,768 IGNITION sys'rsM Joseph R. Harimess, Scotia, N. Y., assignorto General Electric Company, a corporation of New York ApplicationOctober 31, 1941, serial No. 411,370

17 Claims.

This application relates to ignition systems and in particular to suchsystems utilizing relatively low voltage distribution.

An object of my invention is to provide an improved ignition system.

Another object of my invention is to provide an improved low voltagedistribution ignition system utilizing a transformer arranged adjacentthe spark plug for providing high voltage to the spark D 118.

A further object of my invention is to provide an improved convertersystem.

A still further object of my invention is to provide an improvedtransformer device for use in a low voltage distribution ignitionsystem.

Further objects and advantages of my invention will become apparent andmy invention will be better understood from the following descriptionreferring to the accompanying drawing, and the features of novelty whichcharacterize my invention will be pointed out with particularity in theclaims annexed to and forming part of this speciflcation.

In the drawing, Fig. l is a schematic diagram of a low voltagedistribution ignition system embodying my invention; Fig. 2 is alongitudinal sectional view through a combinedcondensertransformer-spark plug provided with features of my invention;and Fig. 3 is a sectional view taken along line 3-3 of Fig. 2.

Referring to the drawing, I have shown a magneto provided with arotatable magnet Ill which is adapted to react electrodynamically with astationary core H of magnetic material about which a primary magnetocoil I2 is inductively arranged. The primary magneto coil I2 isconnected across a condenser l3 and the terminals l4 and i5 of a breakermechanism which is adapted to be operated by a breaker cam i6 mounted ona shaft ii.

The shaft I1 is arranged to be rotated at a predetermined speed relativeto the speed of rotation of the magneto rotatable magnet III. Themagneto also is provided with a secondary winding I 3 arranged on themagneto stationary core member II and inductively related to the primarywinding i2. The terminals of this secondary magneto winding areconnected to ground at l9 and to a rotatable distributor arm which isadapted to complete an electric circuit with a plurality of distributorpoints 2|, each of which is connected to a low voltage distributioncable 22. The magneto provides a source of electrical power supply whichforms part of a converter system and is connected through thedistribution cables 22 to a unit which comprises a combined condenser,transformer and spark plug. This unit is provided with-a cylindricalcasing 23 of electrically conductive material having a substantiallyclosed end 24 at one end thereof and a threaded collar 25 at the otherend thereof which is arranged to engage a complementary threaded portionof a spark plug shell 26. Each distributor cable or lead 22 is insulatedand extends through an opening 21 formed in the end 24 of the casing 23and is electrically connected at 28 to one side or terminal 29 of afixed electrical discharge or spark gap 3|] which is formed between theterminal 29- and another side or terminal 3| of the spark gap. Theterminals 29 and 3| are held in spaced apart relationship by aninsulating member 32 formed with a definite opening in the centralportion thereof, and this provides a definite or fixed spark gap betweenthe spark gap terand a spring seat 35 on the inner side of the casingend 24. This compression biasing spring provides an electrical groundingconnection for the fixed spark gap 3| through the casing 23. In order tosupply a sufiiciently high voltage to provide an electrical dischargeacross the spark gap of the spark plugs of this system, a transformer isprovided which is connected directly to each spark plug. The primary ofthis transformer is formed by a condenser including a plurality ofsections formed by thin electrically conductive plates 36 and 31insulated from each other by thin layers of insulating material 38 and39 such as paper and are wrapped in cylindrical form about a sleeve ofinsulating material 40. The two con denser sections 36 and 31 areconnected across the fixed spark gap 30 in such a manner that currentflowing in the condenser will be substantially in the same direction inall sections thereof.

This arrangement is effected by grounding the outer end of the outercondenser section 36 by electrically connecting it to the electricallyconductive casing 23 through a lead 4| and electrically connecting theinner end of the inner casing to a distributor point 2| and the outerside or terminal 29 of the fixed spark gap 30 by an electrical conductoror lead 42. The secondary of the transformer is formed by a secondarywinding 43 which includes a conductor wound on a core ll of insulatingmaterial and is connected at one end thereof to a distributor point 2|through the fixed spark gap terminal 29 and a distributor lead 22. Theother end of the secondary winding 43 is connected to a terminal contactelement 45 secured in the insulating core 44. The core 44 may be formedas a molded element and the fixed spark gap terminal 29 is provided witha threaded or knurled projection 46 about which the upper end of thecore 44 is molded so as to provide a rigid support for the terminal 29on the core. A spark plug is mounted in the lower end of the casing 23and includes a spark plug electrode 4'! formed on the end of anelectrical conductor 48 which extends upwardly through a core 49 ofinsulating material, such as porcelain, and is provided with an uppercontact terminal element 50 arranged in electrical contact with thetransformer secondary terminal 45. The upper end of the spark pluginsulating core 49 and the terminal 50 extend within the lower portionof the insulating sleeve 40 and an inwardly extending annular flange orcollar 5| formed on the shell 26 extends within a complementary groove52 formed in the insulator 49 for retaining the insulator and the sparkplug electrode in predetermined fixed position within the shell 26. Theunit including the fixed spark gap, the transformer, and the spark plugis adapted to be mounted in the cylinder block of an internal combustionengine and is provided with a terminal supporting sleeve 53 which isthreaded at its upper portion 54 and threadedly engages a complementarythreaded portion 55 formed on the lower end of the shell 26. Thesupporting sleeve 53 is threaded on its outer surface and is adapted tobe secured in a complementary threaded opening in the engine block,thereby providing a rigid support for the spark plug unit and providinga good electrical grounding connection for the various parts of thisunit. The spark plug is provided with a plurality of grounding terminalsor electrodes 56 which form an integral part of the mounting sleeve 53and are spaced apart from the spark plug electrode 41 to provide thedesired spark plug discharge gap therebetween.

In this system, the voltage generated in the magneto secondary coil i8may be from about 800 t 1600 volts and is distributed at this relativelylow voltage to the different spark plug units. The fixed spark gap 30 isconstructed such that it will break down at some voltage lower than thepeak magneto voltage at the lowest operating speed. When an electricaldischarge takes place between the fixed spark gap electrodes 29 and 3i,current circulates around the condenser sections in substantially thesame direction in all sections thereof, thereby inducing a voltage inthe transformer secondary winding 43. In this manner, the condenserprovides the dual functions of a condenser connected across a fixedspark gap and is inductively arranged about the transformer secondarywinding to provide a primary for the transformer. With thisconstruction, the fixed spark gap can be sealed and, if desired, aninert gas can be placed within the surrounding space within the casing23 and a seal can be provided about the distributor lead 22 where itenters the sleeve 23'. Furthermore, since all high voltage is confinedto the inside of the transformer spark plug unit, this unit can befilled with some insulating wax or oil, if desired, and radio shieldingof the leads from the distributor to the spark plug unit may be entirelyeliminated or made much less critical than in a high voltagedistribution ignition system.

While I have illustrated and described a particular embodiment of myinvention, modifications thereof will occur to those skilled in the art.

I desire it to be understood, therefore, that my invention is not to belimited to the particular arrangement disclosed, and I intend in theappended claims to cover all modificat ons which do not depart from thespirit and scope of my invention.

I What I claim as new and desire to secure by Letters Patent 01' theUnited States is:

1. An ignition system including a source of electrical power supply, aspark plug. a transformer secondary winding connected to said sparkplug, a condenser arranged about said transformer secondary winding,means for connecting one side of said condenser to said source orelectrical power supply, and means for connecting the other side of saidcondenser to ground.

2. An ignition system including a source oi electrical power supply, aspark plug, a transformer including a secondary winding connected tosaid spark plug, a primary for said transformer including a condenserinductively arranged about said transformer secondary winding such thatthe passage of current in said condenser induces a voltage in saidsecondary winding, and means for connecting one side of said condenserto said source of electrical power supply.

3. An ignition system including a source of electrical power supply, aspark plug, a transformer including a secondary winding connected tosaid spark plug, a primary for said transformer including a condenserarranged about said transformer secondary winding such that the passageof current in said condenser induces a voltage in said secondarywinding, means for connecting one side of said condenser to said sourceof electrical power supply, and means for connecting the other side ofsaid condenser to ground.

4. An ignition system including a source 01' electrical power supply, aspark plug, a transformer secondary winding connected to said sparkplug, a condenser arranged about said transformer secondary winding, 9,fixed spark gap, means for connecting one side of said condenser to saidsource of electrical power supply and to one side of said spark gap, andmeans for connecting the other side of said condenser to the other sideof said spark gap and to ground.

5. An ignition system including a source of electrical power supply, aspark plug, a transformer including a secondary winding connected tosaid spark plug, a primary for said transformer including a condenserhaving a plurality of sec tions arranged about said transformersecondary winding and being provided with terminals such that thepassage of current in said condenser will be in substantially the samedirection in all sections thereof, and means for connecting one side ofsaid condenser to said source of electrical power pply.

6. An ignition system including a source of electrical power supply, aspark plug, a transformer including a secondary winding connected tosaid spark plug, a primary for said transformer including a condenserinductively arranged about said transformer secondary winding such thatthe passage of current in said condenser induces a voltage in saidsecondary winding, a fixed spark gap, means for connecting one side ofsaid condenser to said source of electrical power supply and to one sideof said spark gap, and means for connecting the other side of saidcondenser to the other side of said spark gap and to ground.

7. A transformer including a primary and a secondary winding, saidprimary including a condenser inductively arranged about said secondarywinding such that the passage of current in said condenser induces avoltage in said secondary winding.

8. A transformer including a primary and a secondary winding,- saidprimary including a condenser having a plurality of sections inductivelyarranged about said secondary winding such that the passage of currentin said condenser induces a voltage in said secondary winding.

9. A transformer including a primary and a secondary winding, saidprimary including a condenser having a plurality of sections arrangedabout said secondary winding and being provided with terminals such thatthe passage of current in said condenser will be in substantially thesame direction in all sections thereof.

10. A transformer including a primary and a secondary winding, saidprimary including a condenser having a plurality of sections insulatedfrom each other and from said secondary winding and inductively arrangedabout said secondary winding such that the passage of current in saidcondenser will be in substantially the same direction in all sectionsthereof and will induce a voltage in said secondary winding.

11. A converter system including a fixed electrical discharge gap, meansincluding a source of electrical power supply for providing electricalimpulses to said electrical discharge gap, a transformer having asecondary winding, and a primary for said transformer including acondenser inductively arranged about said secondary winding andconnected across said fixed discharge gap.

12. A converter system including a source of electrical power supply, afixed electrical discharge gap, means for connecting said fixed gapacross said source of electrical power supply, a

transformer having a secondary winding, a prielectrical power supply, afixed electrical discharge gap, means for connecting said fixed gapacross said source of electrical power supply, a transformer having asecondary winding, and a primary for said transformer including acondenser having a plurality of sections arranged about said secondarywinding and being provided with terminals connected across said fixedgap such that passage ofcurrent in said condenser will be insubstantially the same direction in all sections thereof.

said casing, means for connecting one. side of said spark gap to saidcasing, a transformer in said casing having a secondary windingconnected to the other side of said spark gap, a primary for saidtransformer including a condenser arranged about said transformersecondary winding such that passage of current in said condenser inducesa voltage in said transformer secondary winding, and a spark plug havingan electrode in said casing connected to said transformer secondarywinding.

17. A converter system unit including a casing, a spark gap devicehaving two sides arranged in said casing, means for connecting one sideof said spark gap to said casing, a transformer in said casing having asecondary winding connected to the other side of said spark gap, 9.primary for said transformer including a condenser arranged about saidtransformersecondary winding such that passage of current in saidcondenser induces a voltage in said transformer secondary winding, meansfor connecting one side of said condenser to said other side of saidspark gap, means for connecting the other side of said condenser to saidcasing, and a spark plug having an electrode in said casing connected tosaid transformer secondary winding.

JOSEPH R.

